The present invention relates to computers and, more particularly, to high-availability computing. In this specification, related art labeled “prior art” is admitted prior art; related art not so labeled is not admitted prior art.
High-availability computers are used for applications where the normal amount of downtime suffered by a computer is unacceptable. High-availability computers use redundancy to provide backups for many components such as processors, memory, I/O (input/output) interfaces, power supplies, and disk storage. When one component fails, another similar component is available to take over its function. One approach is to operate identical components in parallel so that if one fails, data is preserved and there is little time lost in switching over from the failed component. Of course, there can be a performance penalty when two components are, in effect, doing the work of one.